State issues bacteria advisories for beaches in Swanzey, Winchester, Greenfield

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Aug. 11—The state environmental services department is advising swimmers to avoid a total of five beaches in Swanzey, Winchester and Greenfield due to elevated levels of certain bacteria.

The N.H. Department of Environmental Services issued a cyanobacteria advisory for Forest Lake in Winchester on July 22, according to the agency's online list of such notices.

On Tuesday, DES posted fecal bacteria advisories for Richardson Park beach on Swanzey Lake, and Camping, Middle and Picnic beaches on Otter Lake in Greenfield State Park.

The cyanobacteria advisory on Forest Lake came after a possible toxin-producing blue-green algae bloom appeared at the surface and along the shorelines of the 85-acre lake, according to DES. The advisory, which is still active as of Wednesday, notes that conditions can change, and the bloom could disperse around the lake.

Levels are tested weekly until blooms fall below DES standards. Sampling conducted Wednesday showed cyanobacteria still above the state's 70,000 cells per milliliter standard, Michele Condon, DES beach inspection program coordinator, said that afternoon.

Cyanobacteria occur naturally in water bodies around the world, and blooms and surface scum can form due to excess nutrients, according to DES. Some cyanobacteria produce toxins that can cause a variety of acute and chronic health issues. DES says people and pets should avoid contact with water experiencing cyanobacteria blooms.

At the Swanzey and Greenfield beaches, water samples collected Monday exceeded the state standard for fecal bacteria, according to the DES advisories, which will remain in effect until bacteria levels fall below the threshold. The state was collecting new samples Wednesday, and results will be available Thursday, according to DES. Beaches are immediately retested until they fall below the state's standards.

Condon said common sources for fecal bacteria include waterfowl such as ducks or geese, domestic animals, agricultural runoff and humans.

Richardson Park beach, which sits on the 108-acre Swanzey Lake, is closed until bacteria levels are back within the recommended range, the town recreation department said in a Facebook post Tuesday. The beach is open only to Swanzey residents, town taxpayers, property owners and employees and guests, as well as guests at inns or hotels in Swanzey, according to the town website.

The three Greenfield beaches are all on the 135-acre Otter Lake in Greenfield State Park. Park officials have posted notices at the beaches, and swimming is not allowed while the advisory is in effect. People can still go to the playgrounds at the beaches or kayak on the water, a park official said Wednesday.

Sentinel staff writer Tom Benoit contributed to this report.